This section provides background information related to the present disclosure and is not necessarily prior art.
Vehicle disc brakes include a brake caliper, a rotor, and brake pads on opposite sides of the rotor. The rotor is coupled to a wheel of the vehicle for common rotation about a central axis. One type of brake caliper is a floating caliper, which typically includes an upper body (housing), a lower body (anchor bracket), and one or more hydraulic pistons configured to move the brake pads into contact with the rotor to decrease the rotational speed of the rotor. The upper body of the caliper moves axially relative to the lower body. Typically, the lower body of the caliper is fixedly mounted to a component of the vehicle that does not rotate about the central axis, such as a steering knuckle for example. Typically, the piston is disposed within a cylinder that is defined by an inboard member of the upper body of the caliper. The piston is axially slidable in the cylinder.
Typically the inboard brake pad is supported by the lower body between the piston and the rotor, and the outboard brake pad is supported by the lower body between the rotor and an outboard member of the upper body of the caliper. Typically, the piston is actuated to engage the inboard brake pad to slide the inboard brake pad axially along the lower body until the inboard brake pad comes into contact with the inboard side of the rotor. Continued actuation of the piston causes the upper body to be pulled inboard until the outboard brake pad contacts the outboard side of the rotor and the rotor is compressed between the inboard and outboard brake pads. Friction between the rotor and the brake pads generally converts rotational energy to heat, causing a decrease in rotational speed of the rotor, and thus the wheel.
Contact between the brake pads and the rotor sends vibrations through the brake pads that travel from the brake pads to the caliper and from the caliper to other parts of the vehicle. In some conditions, these vibrations cause audible noise, such as a moan or squeal during contact between the brake pads and rotor at low rotational speeds or in reverse for example. This low frequency, audible noise is typically referred to as brake moan. Operation of the brake in different conditions causes vibrations of different frequencies that can cause brake moan having different pitches and/or tones during the different conditions. Some operators and/or passengers of the vehicle find this brake moan undesirable.